Distribution and abundance of the cocoa shield bug, Bathycoelia thalassina (Hemiptera: Pentatomidae) in Ghana.
Bathycoelia thalassina (H.-S.) occurs in all cacao-growing regions of Ghana, and in large numbers where Amazon varieties and hybrid selections are cultivated. By means of different sampling methods, the maximum population was estimated as about 5500/ha in September-November. Abundance varied according to the cacao cropping seasons, with increased numbers when young pods were available in late February-April, reduced ones when mature pods were harvested in June-July, a further increase in late August when more young pods were produced, and a sudden fall in December-January at the end of the harvesting period. Since 99% of the nymphs and adults were found on the pods, fans and trunk, control sprays (if necessary) should be limited to the trunk and inner branches where most of the pods are found. Aggregations of B. thalassina occurred mainly along the 10 outer rows of the plantation adjacent to bush and under cacao with a continuous canopy providing light intensities of 500-2150 lux; insecticide treatments should therefore be restricted to these situations.